Need some help.I would like to replace my buicks rear end, with a lower geared, posi unit. At the moment it's a 10 bolt 8.2 non posi with 2.73 gears.

Ideally I would like to go to an 8.5 10 bolt with 3.23-3.73 gears. Is there any vehicles that would have a direct replacement for housing and axle housings? Although I would like to find a full bolt in unit, internals I could find afterwards.